A gap detection tactility test for sensory deficits associated with carpal tunnel syndrome

An automated gap detection tactility test was investigated for quantifying sensory deficits associated with carpal tunnel syndrome (CTS). The test, which involved sensing a tiny gap in an otherwise smooth surface by probing with the finger, had functional resemblance to many work-related tactile activities such as detecting scratches or surface defects. Gap detection thresholds were measured using the converging staircase method of limits paradigm. Sixteen normal subjects between 21 and 66 years of age were tested for studying important factors affecting gap detection thresholds. Actively probing with the index finger had a threshold almost an order of magnitude more sensitive (mean = 0.19 mm, SD = 0.11 mm) than passive touch (mean = 1.63 mm, SD = 0.62 mm), which was similar to two-point discrimination. Average thresholds decreased by 24% as contact force increased from 25 to 75 g. Performance in this tactility test quickly stabilized and showed little learning effects over the period of the test, as evidenced by the lack of significant differences between six replicates. The results were highly repeatable. No significant threshold differences were observed between test and retest trials on different days, or between dominant and non-dominant hands. A contact force of 50 g was recommended as optimal for this test since it required moderate force but resulted in a smaller threshold compared with 25 or 75 g. A companion study was conducted using eight normal subjects and ten subjects diagnosed as having CTS. Average gap detection threshold, when finger probing was allowed, was 0.20 mm (SD = 0.11 min) for the normal subjects and increased two-fold to 0.40 mm (SD = 0.19 mm) for the CTS subjects. Average gap detection threshold, when the finger probing was not allowed, was 1.71 mm (SD = 0.53 mm) for the normal subjects and increased by 48% to 2.53 mm (SD = 0.87 mm) for the CTS subjects. The results suggest that people suffering from CTS may experience similar functional deficits in daily living and work activities. The small inter-subject variability makes this test a candidate for having utility as a monitoring test for loss of cutaneous tactile sensitivity.     

Nonmonotonic behavior of the dose dependence of the radiation effect on cells in vitro exposed to pulsed laser radiation at lambda = 820 nm

The relationship of measures of pressure perception to hand function was evaluated by correlating the results of the Mayo Dexterity Test and a timed object recognition test with the one- and two-point static and moving touch thresholds for the index finger pulp of 44 hands. The Mayo Dexterity Test permits the use of vision, while the object recognition test does not. Quantitative sensory testing was done with the Pressure-specifying Sensory Device. Cutaneous pressure threshold measurements with this device had a statistically significant correlation with the small-object subset of the Mayo Dexterity Test (p < 0.006) and with the object recognition test (p < 0.001), demonstrating that the Pressure-specifying Sensory Device is a valid tool for evaluating the sensory aspect of hand function.     

Cytochemical and biochemical studies on adenylate cyclase activity in preneoplastic and neoplastic liver tissue and cultured liver cells

OBJECTIVE: To assess the accuracy of: 1) distortion product otoacoustic emission (DPOAE) measures for the identification of frequencies at which auditory sensitivity is normal or near normal; and 2) click and nonmasked tone burst-evoked auditory brain stem response (ABR) thresholds for behavioral threshold estimation for children with sensorineural hearing loss characterized by islands of normal sensitivity. DESIGN: DPOAEs and ABRs were recorded from five hearing-impaired and eight normal-hearing pediatric ears. The accuracy with which DPOAEs permitted identification of frequencies at which elevated hearing thresholds were present was examined. ABR and pure-tone threshold differences for the impaired ears were calculated. RESULTS: For three of the five hearing-impaired ears, significant impairments would have been missed based on click-evoked ABR thresholds. One of those hearing-impaired ears provided an essentially normal 500 Hz tone burst-evoked ABR threshold as well. Four of the hearing-impaired ears provided a 500 Hz tone burst-evoked ABR threshold within 10 dB of the respective pure-tone threshold. However, click-evoked ABR and 500 Hz tone burst-evoked ABR threshold data did not adequately delineate the hearing loss configuration for hearing aid frequency response selection. DPOAEs were present at three out of four frequencies from 1000 to 4000 Hz at which sensitivity was normal or near normal (< or =25 dB HL) and absent at 10 out of 11 frequencies at which sensitivity was impaired. The use of DPOAEs to identify frequencies at which sensitivity was normal and the use of tone burst ABR thresholds at frequencies where DPOAEs were absent provided a better estimate of these pure-tone audiograms than was provided by click-evoked and 500 Hz tone burst-evoked ABR thresholds.     

Stability and variability of dream content

The present study investigated the stability and variability, respectively, of selected dream content measures derived from diary dreams. The within-subject correlations were small when dream length was controlled. To obtain sufficient reliability for all scales dream series of 20 dreams or more would be necessary.     

Complex decision rules in categorization: Contrasting novice and experienced performance.

The ability of novice and experienced Ss to learn complex decision rules was tested with 3 categorization tasks. Each task involved 2 categories with exemplars that were normally distributed on 2 stimulus dimensions. Three separate sets of stimuli were used, and in each task the decision rule that maximized categorization accuracy was a highly nonlinear function of the stimulus dimension values. In the 3 tasks, all experienced Ss used highly nonlinear decision rules. Quadratic rules were supported over bilinear rules, and in many cases Ss used nearly optimal decision rules. These findings did not depend on whether the stimulus components were integral or separable. Novice Ss also did not use simple linear rules. A model that assumed Ss tried a succession of different linear rules was also rejected. Instead, novices appeared to use quadratic rules, although less consistently than experienced Ss. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reproducibility of the distribution of carbon-11-SCH 23390, a dopamine D1 receptor tracer, in normal subjects

The reproducibility of [11C]SCH 23390 in PET was studied in 10 normal human subjects. METHODS: The scan-to-scan variation of several measures used in PET data analysis, including the radioactivity ratio, plasma-input Logan total distribution volume (DV), plasma-input Logan DV ratio (DVR) and tissue-input Logan Bmax/Kd values, was determined. RESULTS: There were significant correlations among the radioactivity ratio, plasma-input DVR and tissue-input Bmax/Kd. With the cerebellum as the reference region, these three measures also had high reliability (86%-95%), high between-subject s.d. (7.7%-11.3%) and small within-subject s.d. (2.3%-3.6%), indicating that they are comparable and useful measures for the assessment of dopamine D1 receptor binding. CONCLUSION: The radioactivity ratio and the tissue-input Bmax/Kd may be preferred methods for the evaluation of dopamine D1 receptor binding because these two methods do not require arterial blood sampling and metabolite analysis. Our results show that cerebellum is a reliable reference region for SCH 23390. When the Logan plasma-input function method is used in data analysis for SCH 23390, DVRs rather than total DV values should be used because of the poor reliability of the DV values and their lack of correlation with other measures. Carbon-11-SCH 23390 is thus a reliable and reproducible ligand for the study of dopamine D1 receptor binding by PET.     

Decreased pain threshold and tolerance in patients with chronic tension headache

Nociceptive processing was studied in 40 patients with chronic tension-type headache and in 40 healthy controls. We found that pericranial tenderness recorded by manual palpation was considerably higher in patients than in controls (p < or = 0.0002). Pressure pain detection and tolerance thresholds recorded in the finger, by means of a pressure algometer, were significantly lower in patients than in controls (p < or = 0.0009), and a non-significant similar trend was observed in the temple (p < or = 0.12). Detection and tolerance thresholds were decreased to a similar degree in patients compared with controls, and pain thresholds recorded in the finger and in the temple were highly correlated (r = 0.84, p < 0.0001). The electrical pain threshold at the labial commissure, by means of an electrical stimulator, was significantly decreased in patients compared with controls (p = 0.03). All of the examined pain thresholds were significantly correlated to the pericranial tenderness recorded by palpation (r = -0.35 to -0.53, p < or = 0.03). We conclude that the present finding of a general hypersensitivity to pain stimuli in chronic tension-type headache indicates that central factors play an important role in the pathogenesis of this disorder.     

Oral fluoroquinolones for maintenance treatment of melioidosis

Fifty-three hands with carpal tunnel syndrome had pre- and postoperative evaluations of median nerve distal motor latency (from wrist to thenar muscles) and orthodromic sensory nerve conduction velocity (from thumb and middle finger to wrist). At 6 months we observed a neurophysiological return to normal in all cases with normal preoperative distal motor latency and in about 50% of the hands with preoperative distal motor latency between 4 and 6 ms. Prolongation of the distal motor latency over 6 ms was not followed by return to neurophysiological normality, although some degree of sensory function was restored in the majority of cases.     

The influence of age on the assessment of motor unit activation in a human hand muscle

Two indices of motor unit recruitment, the ramp-force and repetitive-discharge thresholds, were compared in the first dorsal interosseus muscle of ten young and twelve elderly subjects. The purpose was to determine the effect of age on the relationship between the two recruitment thresholds and the spike-triggered average force of motor units. Each subject performed three tasks requiring isometric abduction of the left index finger: a maximum voluntary contraction (MVC), a ramp-and-hold contraction, and a repetitive-discharge task. The elderly subjects used coactivation of the antagonist muscle (second palmar interosseus) more frequently than the young subjects during the ramp-and-hold contraction. Many elderly subjects expressed difficulty with the controlled ramp-down phase of the ramp-and-hold contraction and preferred a coactivation strategy to a derecruitment strategy for this task. There were no differences due to age or gender in the ramp-force thresholds between the various groups. However, the normalized repetitive-discharge threshold was significantly less for the younger subjects and for the male subjects. Nonetheless, the two recruitment thresholds were able to predict the spike-triggered average force with similar success for both the young and the elderly subjects. These data suggest that the recruitment threshold of a motor unit in first dorsal interosseus was characterized equally well by either the ramp-force or repetitive-discharge measurement for both young and elderly subjects but that coactivation was used more frequently by the elderly subjects during the ramp-and-hold task.     

Parrel processing in visual short-term memory.

Visual short-term memory for the contrast and spatial frequency of sinusoidal gratings was measured in a delayed discrimination task in which the 2 stimuli to be compared were separated in time by 1-10 s interstimulus intervals (ISIs). Delayed discrimination thresholds for spatial frequency and contrast were compared, both when the 2 types of thresholds were measured in separate blocks of trials and when the 2 types of measures were randomly intermixed in an uncertainty paradigm, which required participants to process information about both dimensions on each trial. In both cases, accuracy of memory for spatial frequency was independent of ISI, but memory for contrast decreased as ISI increased. Performance was lower in the uncertainty case, but only by an amount predicted by statistical decision theory for independent sources. The results are consistent with a model assuming a set of parallel special-purpose visual discrimination and short-term memory mechanisms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison between two measures of delay discounting in smokers.

Agreement between computer and questionnaire measures of delay discounting in smokers was compared. Correlations between measures for small, medium, or large rewards were significant. Log κ values decreased as the reward delay increased, with values lower for the computer task than the questionnaire, with significant differences for small rewards. The 2 measures were related to smoking rate but not to age, gender, or obesity. The Bland-Altman test of agreement indicated large within-subject differences in κ values between the 2 measures. The size of the difference between the log κ values and magnitude of the log κ values were positively related. Results suggest κ values from the 2 measures are related but may not be used interchangeably. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Across the thin blue line: Police officers and racial bias in the decision to shoot.

Police officers were compared with community members in terms of the speed and accuracy with which they made simulated decisions to shoot (or not shoot) Black and White targets. Both samples exhibited robust racial bias in response speed. Officers outperformed community members on a number of measures, including overall speed and accuracy. Moreover, although community respondents set the decision criterion lower for Black targets than for White targets (indicating bias), police officers did not. The authors suggest that training may not affect the speed with which stereotype-incongruent targets are processed but that it does affect the ultimate decision (particularly the placement of the decision criterion). Findings from a study in which a college sample received training support this conclusion. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the relation between base-rate and cost-benefit learning in simulated medical diagnosis.

Observers completed a series of simulated medical diagnosis tasks that differed in category discriminability and base-rate/cost– benefit ratio. Point, accuracy, and decision criterion estimates were closer to optimal (a) for category d′?=?2.2 than for category d′?=?1.0 or 3.2, (b) when base-rates as opposed to cost–benefits were manipulated, and (c) when the cost of an incorrect response resulted in no point loss (nonnegative cost) as opposed to a point loss (negative cost). These results support the "flat-maxima" (D. von Winterfeldt & W. Edwards, 1982) and competition between reward and accuracy (COBRA; W. T. Maddox & C. J. Bohil, 1998) hypotheses. A hybrid model that instantiated simultaneously both hypotheses was applied to the data. The model parameters indicated that (a) the reward-maximizing decision criterion quickly approached the optimal criterion, (b) the importance placed on accuracy maximization early in learning was larger when the cost of an incorrect response was negative as opposed to nonnegative, and (c) by the end of training the importance placed on accuracy was equal for negative and nonnegative costs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Form of empirical ROCs in discrimination and diagnostic tasks: Implications for theory and measurement of performance.

Presents a sample of empirical relative operating characteristics (ROCs), drawn both from discrimination tasks in experimental psychology and from diagnostic tasks in several practical fields. These illustrative ROCs are seen to be fitted well by a straight line, of varying slope, on a binormal graph. The form of empirical ROCs is consistent with one version of the variable-criterion model provided by signal detection theory and inconsistent both with other versions of that model and with the main threshold models. That form supports the use of certain indices of discrimination accuracy derived from detection theory and substantiates the potential unreliability of others of that heritage and, more importantly, the unreliability of the several accuracy indices in common use that can be shown to imply one or another threshold model. The preferred detection-theory indices of accuracy are ones that accommodate the varying slope of empirical ROCs. These indices are effectively independent of the decision criterion, which can be indexed separately. Measuring both accuracy and the decision criterion appropriately enables the delineation of the dependent variables affected by independent variables in psychological studies and the assessment of the efficacy and accuracy of diagnostic systems. (43 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

IL-15 induces the release of soluble IL-2Ralpha from human peripheral blood mononuclear cells

The present study was designed to investigate the applicability of transient evoked otoacoustic emissions (TEOAEs) as a method of screening for hearing losses among recruits attending obligatory military service. TEOAEs, tympanometry and puretone audiometry were recorded in 95 male recruits. Sixty-one recruits were tested after a 2-month period of gunfire exposure in order to document any permanent change in cochlear function. Screening by pure-tone audiometry showed an unexpectedly high prevalence of hearing losses > 20 dBHL, probably due to technical reasons. Thresholds were corrected using lower thresholds obtained at the end of service or by ENT specialists. The accuracy with which normal and impaired ears could be identified with TEOAEs analysed in frequency bands was determined by decision theory. Impairment was defined as mean hearing thresholds > or = 30 dBHL averaged from three neighbouring frequencies. Adequate accuracy was obtained in the middle frequencies. Further improvement of the technique is needed before it can be deemed suitable for detecting hearing losses at low and high frequencies. TEOAEs are quicker to measure and offer greater objectivity than pure-tone audiometry. A small decrease in TEOAE level was found after the training period. The TEOAEs were highly repeatable and had a higher sensitivity than pure-tone audiometry to detection of small changes in cochlear function under conditions normally found when testing recruits.     

Automated visual field examination in children aged 5-8 years. Part II: Normative values

We determined normative values for the visual sensitivity threshold in 118 children aged 5-8 years, using automated static perimetry (Octopus 2000R, program 32). In addition, 17 normal adults were tested. The children first underwent a familiarization procedure. One week later, quantitative examination was performed according to a specially designed schedule divided into three phases. For each of the 76 points tested, mean thresholds and standard deviations were calculated as a function of age. In contrast to previous studies, sensitivity difference between adults and children over the central 30 degrees of the visual field emerged only for the youngest age groups (5- and 6-year olds). Both the response rate in false-negative trials, and values of a within-subject threshold variability index, suggested that 5- and 6-year-olds' higher thresholds were inflated by non physiological factors, such as vigilance and cognitive processes. For these ages, the data reported here should therefore be considered as an approximation of the upper level of the thresholds. In contrast, our results for 7- and 8 year-old children provided reliable normative values for light sensitivity across the visual field.     

Dynamics of conditioned reflex reorganization in the human visual system

The dymamics of absolute and relative changes in the brightness thresholds of letters recognition was studied in 21 subjects, under conditions of dark adaptation and molecular observation, before and after pairing of one of the letters with electrocutaneous stimulation of the index finger during one session. Isolated electrocutaneous stimulation was applied on the 10th or 35th day after the session. It has been found that after pairings the relative threshold of recognition of the letter previously paired with electrical stimuli (i.e. the threshold in relation to recognition thresholds for the other letters) becomes for three to three and a half hours significantly lower than the initial one. Then there sharply sets in a phase of threshold elevation. Both in the case of double and multiple tests, this phase persists for not less than 35 days. Following an isolated electrical stimulation, a momentary significant lowering of the threshold sets in only for the letter which was paired with it in the first sessions.     

Is More Better? Combining Actuarial Risk Scales to Predict Recidivism Among Adult Sex Offenders.

The present study was conducted to determine whether combining the results of multiple actuarial risk scales increases accuracy in predicting sex offender recidivism. Multiple methods of combining 4 validated actuarial risk scales--the Violence Risk Appraisal Guide, the Sex Offender Risk Appraisal Guide, the Rapid Risk Assessment for Sexual Offense Recidivism, and the Static-99--were evaluated in a sample of 215 adult male sex offenders. These included the intuitively appealing believe-the-negative and believe-the-positive rules, adapted from medical decision making; the combination of absolute decision thresholds across a range of cutoff scores; and the statistical optimization methods of logistic regression and principal components analyses. No combination method provided a statistically significant or consistent advantage over the predictive accuracy of the single best actuarial scale. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Using threshold analysis to improve medical decisions

Physicians can improve their medical decision making by considering the risk-benefit ratio, characteristics of a diagnostic test, and the probability of disease. Several threshold values of probability were defined. The treatment threshold is used when a diagnostic test is not being considered. If the probability of disease is greater than the treatment threshold, then treatment should be administered. If a test is being considered, then the test threshold and the test-treatment threshold should be used to determine if testing is indicated. If the probability of disease is less than the test threshold, then no treatment and no testing are the preferred options. If the probability of disease is greater than the test-treatment threshold, then treatment without testing is preferred. If the probability of disease lies between the test and test-treatment thresholds, the test should be performed.     

The influence of tempering temperature on small fatigue crack behavior monitored with surface acoustic waves in quenched and tempered 4140 steel

Small surface fatigue crack growth in specially designed cantilevered bending samples of high-purity 4140 steel quenched and tempered to various strength levels was investigated. Tempering temperatures of 200 °C, 400 °C, 550 °C, and 700 °C were used to produce a range of yield strengths and microstructures. Crack propagation and crack closure were monitored with a surface acoustic wave ultrasonic technique. The small crack results were compared to those of long cracks in compact tension samples. Small cracks in the 200 °C and 400 °C tempers grew at ΔK levels above their long crack thresholds. Small cracks in the 550 °C tempers grew at ΔK levels slightly below the long crack threshold. The surface cracks in the 700 °C temper grew well below the long crack threshold showing the “small crack effect.” Small crack growth occurred in a very narrowda/dN- ΔK scatter band showing much less variation with microstructure than the long crack data. The differences between the long and small crack data were due to the high, relatively similar closure values for the small cracks and the variation of long crack growth with microstructure. Formerly Graduate Research Assistant, Department of Materials Science and Engineering, Stanford University, Stanford, CA.